Carbonated beverages are produced and sold in various flavors and are marketed in various sized bottles and containers. Generally, larger quantities of carbonated beverages are sold in plastic 2 or 3-liter bottles. These bottles are meant to store and distribute multiple servings of a carbonated beverage over time: hours, days or even weeks. It is often less expensive for a consumer to purchase these larger beverage bottles than the smaller bottles or cans.
In a carbonated beverage, CO2 molecules are constantly coming out of solution and evaporating into the atmosphere above, and vice versa, impinging upon the surface and re-entering solution. The rate at which molecules leave solution is governed by the fluid temperature, and the rate at which molecules enter solution is a function of the partial pressure of the dissolved gas above the fluid, which in this case is CO2. At a certain partial pressure, CO2 molecules in the atmosphere may enter at a rate equivalent to the rate of evaporation, leaving the net concentration in stasis.
The presence of other gas molecules, specifically those that principally comprise air (N2 and O2) may have no effect on the CO2 evaporation rate. N2 and O2 molecules may not intercept escaping CO2 molecules and deflect them back into the liquid. The Ideal Gas Law teaches that the space between individual gas molecules (at other than extreme pressures) is so vast, relatively speaking, that intra-gas interactions can be ignored, which is the underlying principle of Dalton's Law of partial pressures. Dalton's Law states that the total pressure of a gas mixture is the sum of the partial pressures of each constituent gas.
Two other laws that govern dissolved gases are Le Chatlier's principle and Henry's Law. Le Chatlier's principle teaches that for a given partial pressure, lowering the temperature of the liquid will tend to increase the percentage of dissolved gas therein, and Henry's Law instructs that the solubility of a gas in a liquid is a linear function of the partial pressure of that gas above that fluid.
Typically, carbonated beverage bottlers may add about 3.7 volumes of CO2 per volume of beverage. At a temperature of about 72° F., a CO2 partial pressure of approximately 52 psig may be required to maintain 3.7 volumes of CO2 in equilibrium. At the typical refrigerator temperature of 40° F., a much lower pressure of about 24 psig may be required to maintain equilibrium, demonstrating the degree to which temperature governs CO2 solubility. It can be derived that it may require approximately 148,571 psig of air to develop a CO2 partial pressure of about 52 psig.